Explicit Congestion Notification (ECN) and Congestion Feedback Using the Network Service Header (NSH) and IPFIX

Explicit Congestion Notification (ECN) allows a forwarding element to notify downstream devices of the onset of congestion without having to drop packets. Coupled with a means to feed information about congestion back to upstream nodes, this can improve network efficiency through better congestion control, frequently without packet drops. This document specifies ECN and congestion feedback support within a Service Function Chaining (SFC) enabled domain through use of the Network Service Header (NSH, RFC 8300) and IP Flow Information Export (IPFIX, RFC 7011) protocol.